This invention is directed toward adjustably mounting a printing plate cylinder, for example a magnetic cylinder, to a rotatable drive shaft of a printing press or the like.
U.S. Pat. No. 5,819,648 by Megyesi point out some of the problems encountered in using a printing plate cylinder, such as a magnetic cylinder, in printing presses and decorator machines and the like. In practice the printing plate or decorator plate usually has to be changed often which in many cases requires that the printing plate cylinder with attached plate has to be removed from the drive shaft and a new plate installed, or a different cylinder with an attached printing plate installed on the drive shaft. Each time the printing plate is changed it may require some small amounts of adjustment both axially and circumferentially to bring the indicia on the new printing plate into proper registration with respect to other printed indicia. The Megyesi ""648 patent describes some of the problems associated with removal and replacement of the printing plate cylinders on a decorator machine and the need to have adjustments available to bring the indicia on the printing plate into close registration with the other printed indicia. As is well-known in the commercial field and as mentioned in the ""648 patent, some printing presses or decorator machines have straight or right angle cylindrical rotatable shafts and others have tapered shafts. The untapered shaft generally allows for easier adjustability but repeated replacement usually causes some wear to the bore of the printing plate cylinder and/or the shaft. The tapered shaft has the advantage of minimizing the amount of wear caused by repeated replacements but lacks adjustability. The ""648 patent utilizes an inner member or sleeve which has a tapered or conical shaped axial bore to engage a tapered rotatable drive shaft. The outer surface of the sleeve is untapered to engage the untapered axial bore of an outer sleeve or printing plate cylinder. In this arrangement to bring the printing plate into registration the outer printing plate cylinder is adjusted with respect to the inner sleeve which remains mated to or engaged with the tapered shaft. To gain the advantage of a tapered shaft when the printing plate or decorator plate has to be changed the entire combination of the inner member or sleeve and the outer member or printing plate cylinder (as well as the attached printing plate) is removed from the shaft and replaced with a new similar combination with a new printing plate or a new printing plate is replaced on the printing plate cylinder and the same unit or assembly is then reinserted on the tapered drive shaft.
Another embodiment of an adjustable printing plate cylinder by the same applicant as the instant application is a printing plate cylinder with a linear bearing press-fitted into the bore for engaging an untapered rotatable printing press drive shaft. The linear bearing minimizes the wear which normally is encountered when mounting the cylinder on an untapered drive shaft and also allows for both axial and circumferential adjustment of the printing plate cylinder as needed.
A sleeve member has an untapered bore for engaging and surrounding an untapered rotatable drive shaft of a printing press or the like and fits snugly but adjustably on the untapered drive shaft. The outer surface of the sleeve is tapered. A printing plate cylinder has a correspondingly tapered axial bore for engaging the outer surface of the sleeve member. When replacing a printing plate, only the printing plate cylinder, with attached printing plate, is removed from the sleeve member which remains engaged with the drive shaft. The tapered coupling between the sleeve member and the printing plate cylinder produces some benefits attributable to a tapered shaft yet at the same time, the untapered bore of the sleeve member engaging the untapered shaft retains the benefit of the adjustability feature associated with an untapered drive shaft. When a printing plate is changed, only the printing plate cylinder (with attached printing plate) is removed. Because of the tapered bore of the printing plate cylinder it can then be replaced onto the outer tapered surface of the sleeve member so that the printing plate is close to the ultimate registration. The sleeve member can then be adjusted both axially and circumferentially with respect to the drive shaft as necessary to bring the printing plate into more accurate registration.
In the aforementioned Megyesi device, because of the weight of the assembly which has to be removed from and replaced on the shaft when replacing a printing plate, the outer sleeve of the Megyesi device preferably is made out of a lighter weight metal such as aluminum. By comparison, since the instant invention requires only that the outer printing plate cylinder be removed and replaced for changing the printing plate it can be made out of a heavier metal such as steel. The parts made of steel are more uniform and are more stable (hold their dimensions better) and can be machined more accurately and precisely. This results in a significant savings in manufacturing costs and registration can be more accurate and precise.
In the ""648 patent, when changing printing plates both the inner and outer members are removed from the shaft and the assembly is usually cleaned (to remove ink and other materials). The cleaning process may result in dissolving surface lubrication between the members which is used to keep the members from binding up. Therefore, the usual practice is to separate the members after they are removed from the shaft and then relubricate after cleaning. In the instant invention only the printing plate cylinder is removed and cleaned before replacing on the sleeve. The lubrication is between the shaft and the bore of the sleeve which remains untouched and unchanged during replacement of a printing plate. Therefore, relubrication is not required.